September weather forecast
Grass Valley, OR

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Weather in September

The first month of the autumn, September, is still a pleasant month in Grass Valley, Oregon, with temperature in the range of an average high of 73.2°F (22.9°C) and an average low of 52.7°F (11.5°C).

Temperature

The shift from August to September involves a decrease in the average high-temperature, from a moderately hot 83.3°F (28.5°C) to a pleasant 73.2°F (22.9°C). September's average low-temperature reading in Grass Valley, Oregon, settles at a cool 52.7°F (11.5°C).

Humidity

In Grass Valley, the average relative humidity in September is 54%.

Rainfall

In Grass Valley, in September, it is raining for 5.8 days, with typically 0.35" (9mm) of accumulated precipitation. Throughout the year, in Grass Valley, there are 112.2 rainfall days, and 10.91" (277mm) of precipitation is accumulated.

Snowfall

April through October are months without snowfall in Grass Valley.

Daylight

The average length of the day in September in Grass Valley is 12h and 31min.
On the first day of September, sunrise is at 6:25 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 7:01 am and sunset at 6:44 pm PDT.

Sunshine

In Grass Valley, the average sunshine in September is 10.8h.

UV index

In September, the average daily maximum UV index in Grass Valley is 4. A UV Index reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV rays for the average person.
Note: During September, 4 as the daily maximum UV index converts into the following advice:
Take measures. Individuals with light skin might experience burns in under 30 minutes. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear.
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Frequently asked questions

What is the average September temperature in Grass Valley?

During September, Grass Valley experiences an average high-temperature of 73.2°F (22.9°C) and a low-temperature of 52.7°F (11.5°C). In August, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which takes the relative humidity and factors it into the air temperature reading, is computed to be 84.2°F (29°C).

What is the average humidity in September in Grass Valley?

The average relative humidity in September in Grass Valley is 54%.

How much does it rain in Grass Valley in September?

In Grass Valley, Oregon, during September, the rain falls for 5.8 days and regularly aggregates up to 0.35" (9mm) of precipitation.

When it does not snow in Grass Valley?

April through October are months without snowfall in Grass Valley, Oregon.

What is the average length of the day in September in Grass Valley?

In September, the average day length is 12h and 31min.

What time are sunrise and sunset in September in Grass Valley?

On the first day of September, sunrise is at 6:25 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 7:01 am and sunset at 6:44 pm PDT.

How many hours of sunshine does Grass Valley have in September?

In September, the average sunshine duration in Grass Valley, Oregon, is 10.8h.

What is the UV index reading in September in Grass Valley?

In Grass Valley, Oregon, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health risk from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Grass Valley, OR

Average temperature in September - Grass Valley, OR
  • Average high temperature in September: 73.2°F

The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is December (37.4°F).

  • Average low temperature in September: 52.7°F

The month with the highest average low temperature is August (57.9°F).
The coldest month (with the lowest average low temperature) is December (27°F).

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Average pressure in September
Grass Valley, OR

Average pressure in September - Grass Valley, OR
  • Average pressure in September: 29.98"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.95"Hg).

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Average wind speed in September
Grass Valley, OR

Average wind speed in September - Grass Valley, OR
  • Average wind speed in September: 6mph

The windiest month (with the highest average wind speed) is June (7.9mph).
The calmest months (with the lowest average wind speed) are January and December (5mph).

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Average humidity in September
Grass Valley, OR

Average humidity in September - Grass Valley, OR
  • Average humidity in September: 54%

The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is August (46%).

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Average rainfall in September
Grass Valley, OR

Average rainfall in September - Grass Valley, OR
  • Average rainfall in September: 0.35"

The wettest month (with the highest rainfall) is January (1.93").
The driest month (with the least rainfall) is July (0.12").

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Average rainfall days in September
Grass Valley, OR

Average rainfall days in September - Grass Valley, OR
  • Average rainfall days in September: 5.8 days

The month with the highest number of rainy days is March (14.3 days).
The month with the least rainy days is July (2.9 days).

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Average snowfall in September
Grass Valley, OR

Average snowfall in September - Grass Valley, OR
  • Average snowfall in September: 0"

The month with the highest snowfall is February (2.87").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in September
Grass Valley, OR

Average snowfall days in September - Grass Valley, OR
  • Average snowfall days in September: 0 days

The months with the highest number of snowfall days are February and December (3.9 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).

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Average daylight in September /
Average sunshine in September
Grass Valley, OR

Average daylight in September / Average sunshine in September - Grass Valley, OR
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).

  • Average sunshine in September: 10h and 5min

The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 0min).

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Average sunshine days in September
Grass Valley, OR

Average sunshine days in September - Grass Valley, OR
  • Average sunshine days in September: 22.3 days

The month with the most sunshine days is July (27 days).
The month with the least sunshine days is February (12.3 days).

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Average UV index in September
Grass Valley, OR

Average UV index in September - Grass Valley, OR
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in September
Grass Valley, OR

Average cloud cover in September - Grass Valley, OR
  • Average cloud cover in September: 17

The month with the most cloud cover is January (Cloud cover 49).
The months with the least cloud cover are July and August (Cloud cover 9).

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Average visibility in September
Grass Valley, OR

Average visibility in September - Grass Valley, OR
  • Average visibility in September: 6mi

The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (5mi).

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Grass Valley, Oregon, USA

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